--Disease Characteristics-- Histologically proven intracranial tumor OR Pathologically confirmed cancer with metastases to the brain OR Newly discovered brain lesions that are amenable to stereotaxic biopsy No more than 3 measurable tumors Only 1 tumor more than 3 cm in diameter that requires radiosurgery allowed No tumor more than 4 cm in diameter No tumor that involves more than 50% of the brain stem --Prior/Concurrent Therapy-- Biologic therapy: Not specified Chemotherapy: Not specified Endocrine therapy: Concurrent corticosteroids allowed Radiotherapy: Prior cranial radiotherapy allowed Surgery: Radiosurgery to other nonstudy intracranial lesions allowed Prior biopsy and/or subtotal or near-total resection allowed --Patient Characteristics-- Age: 18 and over Performance status: Karnofsky 70-100% OR ECOG 0-2 Life expectancy: More than 3 months Hematopoietic: WBC at least 3,000/mm3 Absolute granulocyte count at least 500/mm3 Hemoglobin at least 10 g/dL Platelet count at least 50,000/mm3 Hepatic: SGOT or SGPT no greater than 2.5 times upper limit of normal (ULN) PT and PTT no greater than 1.5 times ULN No clinically significant hepatic dysfunction Renal: Creatinine no greater than 1.3 times ULN Cardiovascular: No clinically significant cardiac dysfunction Pulmonary: No clinically significant pulmonary dysfunction Other: Not pregnant or nursing Negative pregnancy test No clinically significant systemic illness or serious infection that would preclude study compliance No other organ dysfunction that would preclude study compliance No history of psychiatric disease No allergy to contrast agent Papilledema and motor or sensory deficits allowed No contraindications to MRI (e.g., aneurysm clip, implanted neural stimulator, implanted cardiac defibrillator, cochlear implant, ocular foreign body or implant, or insulin pump)